Prologed PT and Normal PTT may be seen in -

PT measures extrinsic system and common pathway APTT measures intrinsic and common pathway In thrombocytopenia , coagulation pathway is not affected. So no change in PT , APTT In DIC and vit k deficiency both PT and APTT are prolonged Reference : Harsh Mohan textbook of pathology, 7th edition.Pg no.314,317